Semi-Autonomous AWD Transmission Vehicle using Lego Technic - Phase 1

Idea

Create a Lego Technic based vehicle with AWD transmission. The vehicle should avoid front, sides and back collisions using Sensors(Ultrasonic, Infrared etc). 

Control vehicle using a remote. The remote should offer functions like steering, speed, transmission. Remote should also show relevant information like sensor readings, steering, speed, transmission etc. 

Execution

Chassis

I used Formula off-roader 42037 as base and reused most of its parts. For front steering with differential, I took idea from The Unofficial LEGO Technic Builder's Guide, 2nd Edition book.

The chassis uses two l-motor-88003 motors in coupling mode, one servo for steering and one servo to shift gears. These motors are powered using AA battery box.

I used Extension Wires and attached Dupont Connectors to it. This way, motors can be re-used in pure Lego projects. I used this tool for crimping

AWD Transmission

I modified Sequential AWD 4-speed gearbox with V8 fake engine and fit it in the chassis. I also replaced two gear changing knobs with gears. I was hoping that gear would help in gear shift using servos but I failed to achieve what I wanted. Will talk about it later

Motor Driver Board

I used All-in-one Robotics Board for BBC micro:bit. It's nice board with ability to drive four motors. This board can get input from AAA or AA battery box due to it's high input voltage.

Remote

For now, I used Yahboom Gamepad Joystick Breakout Board for BBC Micro:bit. But my plan is to use elecfreaks-joystick-bit with iic-oled later.

Current remote is showing Power/Speed level, Gear shifts and steering using Micro:bit led screen.

To-Do

1. Fix steering angle, for now it's ratio is 1.67:1
2. The overall build is not sturdy. It's front wheels wobbles on steering
3. Gear slips when driving on slope or climbing high objects
4. Gear doesn't shift to 2 and 4 as i am not able to step servo between 0 and 180
5. Attach steering with servo   
6. Attach Sensors
7. Beautify the model

Demo

Pictures

Video

Driving

Gear Slip

Driving Slope

Climbing Object

Code

Remote

Remote Code Yahboom

Car

Car Code Kitronik

***Update-1***

Fixed clicking sound in gear system by putting a beam next to Differential

Videos

No click going up hill

No click on climbing object

***Update-2***

Fixed stepping through servo. Lego PF Servo responses to 1150Hz PWM and uses duty cycles to step through its 15 positions. I will post a bit details about it in separate blog.

I modified code for the shield to work with Lego PF. The code is available here